The invention relates to a fuel tank made of plastic for motor vehicles, wherein installations are located in the interior of the fuel tank. The wall of the fuel tank may consist of a single blow-molded piece having a sufficiently large opening or of two pressed or deep-drawn plastic shells which are subsequently joined together. The mentioned forming processes use a mold, wherein the plastic is molded at a warm state. The walls may also be multilayered in order to minimize permeation of fuel vapors. The installations may be of different kinds; usually they are parts of a venting system, such as valves, separators, debubbling tanks and/or float chambers and pipes or tubes connecting these.
In the case of conventional fuel tanks made of plastic, the parts of the venting system are individually mounted at the inside of the upper shell either by welding (see, for example, EP 1 310 715 A1) or by attaching them to weld crowns secured in through-holes of the shell (see, for example, EP 1 084 889 A1). In any case, however, the individual parts are interconnected or connected to the atmosphere through pipes. The parts or weld crowns all have small surfaces.
Mounting and connecting the individual parts of the venting system and of the connection pipes thereof to the inside of the plastic shell are labor-intensive—and therefore expensive—manufacturing processes. This is true especially in cases where the fuel tank is indented for reasons of space economy in a passenger car and where the walls or the plastic parts of the walls have a large spatial depth. In these cases the pipes or tubes are freely suspended in the interior of the fuel tank and may vibrate, which renders them susceptible to failure and may generate rattling noises. Attaching them to the walls further increases the amount of labor required during manufacturing. Moreover, the cross section of the pipes or tubes and their radius of curvature are limited. The former impairs functionability, the latter restricts design flexibility.
DE 10 2006 059 799 A1 discloses a fuel tank made of plastic, wherein a surge container is attached at the bottom of the fuel tank and profiled sections are attached at the top wall of the fuel tank in such a manner that they have flanges with welding projections, which are pressed into the inner wall of the tank part while it is warm and lying in the mold and are integrally bonded thereto in this way. The surge container and the profiled sections are not associated in any way. There is no connection with any functional parts.
The object of the invention to form the installations of a fuel tank made of plastic such that requirements are fulfilled, while expenditure for labor, tools and logistics are kept to a minimum, and that their functionality is improved, while great economy of space and design flexibility are achieved. The installations are also to be suitable for fuel tanks of complex shapes (especially for fuel tanks having a deeply profiled top wall) and should not make a rattling noise.